Fob ascebtaining the direction oei sounds in fog



il Niki? i n strass N'r orrion. v

INSTRUMENT FOR ASCERTAINING THE DIRECTION 0F SOUNDS IN IEOGr,` &`c.

Specification o Letters Patent No. 23,718, dated April 19, v1859.

Zo all zr/wm 'it may concern:

Be it known that I, BENJAMLN R. SMITH, or the city and county of Philadelphia and State of lem'isylvania, have invented or discovered a nenvv and useful improvement in the mode of correctly ascertaining the direction of sounds at sea in foggy or thick weather, as, for instance, the ringing of a bolic reflector, and Fig. 2 represents a secl' tion through the same, which two figures will tully illustrate my invention or discovery. y

It is a great desideratum for persons at sea, to be able to judge correctly of the direction of sounds, in a fog, or other thick weather, as it is utterly impossible to determine, judging by the unassisted ear, Whether t-he sound of a fog bell, for instance, comes from the right or lett hand side, so that these only serve to warn of danger without showing' its position.

By using a parabolic rellector of the proper size, and applying the ear tonits tocus, the intensity of the sound Will reach its maximum, when the reflector is pointing directly toward the bell, or in other words, When the rays ot sound are entering` on a line with the axis ol the curve-l thus ascertain the position ot' a tog bell, or other Source ot' sound.I and at the same time hear it more dxstinrtly at a given distance, or at a greater distance with the same distinctncss, and this constitutes my invention.

The principle of the invention is fully illustrated in the parabolic reflectors used in light houses and the law which is goed in acoustics as in optics, that the angles of incidence and reflection are equal. l3nt while a pai-aboli(l form is the best, l do not confine my invention to that form alone, but mean to claim any form of curve that will collect `the rays or waves of sound to a focus, point, or center, Where the ear may be placed, and' when all the sound entering the reflector trom the point d, lines be drawn to any` points e, e', e, e" &c., and from these points lines parallel With the axis a, c, as at f, j', f", &c., be drawn, 1t will repre-- senthow the Waves or rays of sound, coming in the direction ofV the lines f f f, &c,

will be rellected at an. angle equal to that ativ'hich they strike. the parabola, and be brought to the focus' d and at this point an opening is made, fitte with an ear piece n which is held to theear of the .listener-a handle m being provided for this purpose.

It may be doubted Whether in a heavy blow, this instrument would be available, for the purpose. But in a gale of Wind, a fog bell `in many cases can not be heard. at all, and when a fog bell is of any service, then this reflector will not only detect its position, but. will. increase its vibrations on the ear, so that the sound may be heard at a greater' distance than without it. The reverse, exactly, of this eff'ect and operation would take place were a bell to be hung in the focus of a parabolic reflector, for the waves of sound 'would then be thrown in a given direction in obedience to the law of the angle of incidence being equal to the.

angle of reflection, and by this means the sound of the hell or whistle ,Would be thrown oit' in lines parallel to each other or as nearly so as may be expedient and thus the body of the sound carried to a much greater distance than is at present the case.

The curved portion vof the reiiector may be made of metal of any kind, and the part c, c, may be of thin Wood,vor it may beentirely ot' metal, or any other materialsuflieiently light and strong, and that 'will rel fleet the waves or rays of sound.

Havingr thus fully described the nature and object of my invention, What I claim as new, and desire to secure by Letters Patent is reflector made of suitable material, and

of such a form or shape that it will collect lines. ned be, the sound Uf ai bell 0i' all the rays au' waves of sound ntering it? 1 whistle which muy be planted :1L the focus of w a focus, whcn it may be pointed toward the said l'el'lccm', substantially am described. 10

the dlecton'from whence the .sound wines` l BENJAEHN R. SMVAI. for the puz'pse 0f ascertaining the direc: 'm11 0f ne source of sufh sound?, and conveys-dy, uf throwing o' from l'eiecm', in pamlel Vv 1111 asses I. SPERRY vILLIN/j, JAMES (if. nnmsic. 

